Method and system for providing a proxy media service

ABSTRACT

A method for providing a push-to-talk proxy media service includes receiving a plurality of monitored push-to-talk communication streams over a high bandwidth connection and mixing the plurality of monitored push-to-talk communication streams into a mixed communication stream. The method also includes transmitting the mixed communication stream to a user endpoint over a low bandwidth connection.

RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No.11/267,645, entitled “METHOD AND SYSTEM FOR PROVIDING A PUSH-TO-TALKCOMMUNICATION SESSION”, filed concurrently with the present application,and to U.S. patent application Ser. No. 11/267,693, entitled “METHOD ANDSYSTEM FOR PROVIDING A PUSH-TO-TALK COMMUNICATION SESSION USING ACONTROL ENDPOINT,”, filed concurrently with the present application.

TECHNICAL FIELD OF THE INVENTION

This invention relates in general to communication systems and, moreparticularly, to a method and system for providing a proxy mediaservice.

BACKGROUND OF THE INVENTION

Many public and private groups, such as security and safety personnel(e.g., police, fire fighters and ambulance drivers) use variouscommunication networks of differing technologies and types forcommunication. Many networks utilize land mobile radios communicatingthrough push-to-talk technologies. However, communications amongdifferent endpoints of different networks such as endpoints of differentpolice, fire or other security networks may be difficult. Collaborationbetween the different agencies and networks tends to be ad hoc andinefficient. When achieved, it often involves laborious manualintervention. Organizations working towards interoperability solutionsinclude Raytheon JPS Communications, IP Blue, Twisted Pair, M/A-COM,Motorola and Cisco Systems.

In addition, many networks of public and private groups, such assecurity and safety personnel, utilize push-to-talk technology to enablecommunications among members of a particular group. Groups members maycommunicate using push-to-talk endpoints, such as land mobile radios.These endpoints are typically half duplex endpoints such that theycannot support both outgoing and incoming communications at one time.

SUMMARY OF THE INVENTION

The present invention on provides a method and system for providing aproxy media service that substantially eliminates or reduces at leastsome of the disadvantages and problems associated with previous methodsand systems.

In accordance with a particular embodiment, a method for providing apush-to-talk communication session includes facilitating a push-to-talkcommunication session among a full duplex endpoint supportingsimultaneous two-way communication and a plurality of half duplexendpoints. Communications are received from and transmitted to the fullduplex endpoint along a two-way communications path. The method includesblocking communications received from the full duplex endpoint while oneof the plurality of half duplex endpoints has floor control in thecommunication session and receiving from the full duplex endpoint in thetwo-way communications path a floor control signal comprising a requestto transmit communications in the communication session. The methodincludes, in response to receiving the floor control signal, providingfloor control to the full duplex endpoint and transmitting to theplurality of half duplex endpoints communications received from the fullduplex endpoint.

In accordance with another embodiment, a method for providing apush-to-talk communication session using a control endpoint includesfacilitating a push-to-talk communication session among a full duplexendpoint supporting simultaneous two-way communication and a pluralityof half duplex endpoints. Communications are received from andtransmitted to the full duplex endpoint along a two-way communicationspath. The method includes blocking communications received from the fullduplex endpoint while one of the plurality of half duplex endpoints hasfloor control in the communication session and receiving, from a controlendpoint separate from the full duplex endpoint, a floor control signalcomprising a request to transmit communications in the communicationsession. The method includes, in response to receiving the floor controlsignal, providing floor control to the full duplex endpoint andtransmitting to the plurality of half duplex endpoints communicationsreceived from the full duplex endpoint.

In accordance with another embodiment, a method for providing apush-to-talk proxy media service includes receiving a plurality ofmonitored push-to-talk communication streams over a high bandwidthconnection and mixing the plurality of monitored push-to-talkcommunication streams into a mixed communication stream. The method alsoincludes transmitting the mixed communication stream to a user endpointover a low bandwidth connection.

Technical advantages of particular embodiments include the ability of auser of a full duplex endpoint to communicate in a push-to-talkcommunication session with half duplex endpoints. Moreover, in somecases the user may utilize an endpoint different from the full duplexendpoint to control the floor in a push-to-talk communication session.Moreover, particular embodiments provide a proxy media service to enablea user to monitor a plurality of communication sessions, such as aplurality of PTT communication sessions, over a connection with aninteroperability system through a low bandwidth network, such as a WAN.Thus, the ability to monitor many communication sessions is provided tousers despite the lack of high bandwidth access to the interoperabilitysystem. This may provide users with the ability to monitor suchcommunication sessions from home, for example, over a DSL or otherconnection instead of having to monitor from a company's or otherorganization's high bandwidth LAN.

Other technical advantages will be readily apparent to one skilled inthe art from the following figures, descriptions and claims. Moreover,while specific advantages have been enumerated above, variousembodiments may include all, some or none of the enumerated advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and itsadvantages, reference is now made to the following description, taken inconjunction with the accompanying drawings, in which:

FIG. 1 illustrates a communication system with various communicationnetworks and an interoperability system, in accordance with a particularembodiment;

FIG. 2 illustrates an example interoperability system, in accordancewith a particular embodiment;

FIG. 3 illustrates an example system for providing a push-to-talkcommunication session among a full duplex endpoint and a plurality ofhalf duplex endpoints, in accordance with a particular embodiment;

FIG. 4A illustrates an example system for providing a push-to-talkcommunication session using a control endpoint, in accordance with aparticular embodiment;

FIG. 4B illustrates another example system for providing a push-to-talkcommunication session using a control endpoint, in accordance with aparticular embodiment;

FIG. 5 illustrates an example system for providing a push-to-talk proxymedia service, in accordance with a particular embodiment;

FIG. 6 illustrates a method for providing a push-to-talk communicationsession, in accordance with a particular embodiment;

FIG. 7 illustrates a method for providing a push-to-talk communicationsession using a control endpoint, in accordance with a particularembodiment; and

FIG. 8 illustrates a method for providing a push-to-talk proxy mediaservice, in accordance with a particular embodiment.

DETAILED DESCRIPTION

FIG. 1 illustrates a communication system 10, in accordance with aparticular embodiment. Communication system 10 includes communicationnetworks 24 a-24 e, interoperability system (IS) 20 and endpoints 22a-22 c. IS 20 is able to facilitate interoperable communication sessionsbetween and among various communication devices, such as endpoints ofcommunication networks 24 and endpoints 22. IS 20 uses a systemsapproach to offer a framework based on IP protocols and services toimmediately achieve secure voice, video and other data interoperabilityamong communication endpoints and networks utilizing differenttechnologies.

Particular embodiments provide a user of a full duplex endpoint tocommunicate in a communication session with push-to-talk (PTT) halfduplex endpoints. In general, a full duplex endpoint is capable ofsending and receiving communications at the same time (e.g., along a2-way communications path). A half duplex endpoint can only send orreceive communications at the same time (e.g., it cannot supportsimultaneous 2-way communication). Thus, to effectively communicate witha half duplex endpoint, only one party can talk at any one time as onlyone channel is available. Therefore, to speak in a PTT manner withanother half-duplex PTT endpoint, a user must “control the floor” bypressing and/or otherwise activating a PTT button which sends a signalto other PTT endpoint(s) on the channel or frequency to let them knowthat the user has control of the floor. This is in contrast to fullduplex endpoints, such as typical telephones which can both send andreceive communications at once because outgoing and incomingcommunications are sent along separate channels or, in other words,along a 2-way communications path.

Particular embodiments facilitate interoperable PTT communications amongPTT half-duplex endpoints and a full duplex endpoint through, forexample, an interoperability system. The system provides a user of thefull duplex endpoint with various methods for controlling the floor inorder to communicate with the half duplex endpoints. In some embodimentsa DTMF or other signal may be communicated through the maincommunications path through which normal media communications arecarried. In some cases a separate control endpoint may be used for thefloor control signal. When the full duplex endpoint does not have floorcontrol in a PTT session, the system may block any communications fromthe full duplex endpoint to allow the half duplex endpoints tocommunicate in the session. Thus, PTT functionality is provided to fullduplex endpoints for interoperable communications with half duplex PTTendpoints of other communication networks.

Moreover, particular embodiments provide a proxy media service to enablea user to monitor a plurality of communication sessions, such as aplurality of PTT communication sessions, over a connection with aninteroperability system through a low bandwidth network, such as a WAN.A proxy media system may mix streams from the plurality of communicationsessions for effective communication to the user over the low bandwidthnetwork. Thus, the ability to monitor many communication sessions isprovided to users despite the lack of high bandwidth access to theinteroperability system. This may provide users with the ability tomonitor such communication sessions from home, for example, over a DSLor other connection instead of having to monitor from a company's orother organization's high bandwidth LAN.

In the illustrated embodiment, communication networks 24 a and 24 dcomprise radio networks (RNs), communication network 24 b comprises alocal area network (LAN), communication network 24 c comprises a PSTNand communication network 24 e comprises an IP network. It should beunderstood, however, that communication system 10 may comprise anynumber of IP or non-IP communication networks of any wireless orwireline form capable of communicating audio and/or videotelecommunication signals, data, and/or messages, including signals,data or messages. Communication networks 24 a-24 e may include anynumber and combination of segments, nodes and endpoints to enablecommunication among network devices and components. Communicationnetworks 24 a-24 e may be distributed locally or across multiple citiesand geographic regions. Nodes may include any combination of networkcomponents, gatekeepers, call managers, conference bridges, routers,hubs, switches, gateways, base stations, endpoints or other hardware,software or embedded logic implementing any number of communicationprotocols that allow for the exchange of data in communication system10. Segments 30, which may comprise any suitable wireless or wirelinecommunication links, including one or more communication networks (e.g.,WANs) as appropriate, couple various networks with each other and withendpoints 22 and IS 20. In particular embodiments, segments may includegateways for facilitating communication between various networks, suchas an LMR gateway between radio network 24 a and IP network 24 e.

In some cases, users of endpoints of one of communication networks 24a-24 e may communicate with endpoints of another of communicationnetworks 24 a-24 e through facilitation provided by IS 20. A radionetwork, such as radio network 24 a or 24 d, may support communicationamong portable mobile station endpoints, such as land mobile radios(LMRs), using any suitable communication methods or features, such ascellular and push-to-talk (PTT). Communication networks 24 a-24 e maycomprise networks of particular groups or agencies (e.g., amunicipality's police department network or a company's network),whether operational with respect to a particular area or otherwise.

IS 20 enables, facilitates and/or provides for interoperablecommunication among communication endpoints and devices, such as LMRs,cellular phones, IP phones, PCs, PDAs, PSTN phones, video monitors,cameras and sensors of one or more communication networks (e.g.,communication networks 24 a-24 e) using Internet Protocol. Suchendpoints may comprise IP or non-IP-enabled endpoints. In particularembodiments, IS 20 may control gateways (for example, of segments 30) inorder to map radio frequencies of particular mobile radio endpoints toIP addresses for communication to other types of radio endpoints or IPdevices. For example, a particular gateway may be able to receivecommunications from various types of endpoints (e.g., on various typesof communication networks) and may convert such communications fortransmission to other types of endpoints. IS 20's control of the gatewaymay control the various endpoints and/or networks that receiveparticular communications, depending on system functionality andconfiguration as further discussed below. As indicated, such control mayinclude the mapping of communications and endpoints to IP addresses forinteroperable communication. In some embodiments, IS 20 may host audioconferences that bridge communications received from endpoints. Asindicated above, communication system 10 (including IS 20) may includeany suitable number or type of gateways (e.g., LMR and PSTN gateways),servers (e.g., multipoint conference servers), switches, routers,firewalls, access points, processors, memory or other hardware, softwareor encoded logic to provide functionality described herein. IS 20 iscoupled to communication networks 24 a-24 d and endpoints 22 through IPnetwork 24 e, which may comprise any suitable IP network.

As indicated above, IS 20 uses IP to enable communication amongendpoints of various networks. The manner in which IS 20 facilitatescommunications among endpoints may vary according to location and systemor operational needs. For example, IS 20 may communicate with endpointsusing multicast IP addresses assigned to an endpoint of a communicationnetwork, a group of endpoints of a communication network or one or moreendpoints of multiple communication networks or alternatively using apeer to peer dialed connection or a nailed dialed connection. A group ofendpoints may be combined into a virtual talk group for communicationusing a particular IP address. As an example, the virtual talk group maybe assigned a multicast IP address through which users of variousembodiments may communicate on the talk group. The use of multicast IPaddresses allows IS 20 to facilitate communications among communicationdevices and endpoints of various communication networks to provideaudio, data, video and control network interoperability. As anadditional example, in some cases multicast streams (e.g., utilizingmulticast IP addresses) may be used. In some cases nailed dialedconnections, such as those using SIP protocol, may be used forcommunication among endpoints and with IS 20. Various embodiments maycombine communication methods to facilitate communication amongendpoints. For example, in some cases certain endpoints of a virtualtalk group may participate in the talk group through a multicast IPaddress while other endpoints may utilize a nailed SIP connection. IS 20may control this participation, such as by controlling gateways,multipoint conferences and the mapping of communications to IPaddresses.

IS 20 may be utilized and implemented in any number of market segments,such as enterprise safety and security (e.g., loss prevention),transportation, retail, public safety and federal agencies in order toprovide radio and non-radio network interoperability within and betweensuch market segments. As indicated above, such network interoperabilityincludes the interoperability of push-to-talk voice technology withinvarious networks and the interoperability between push-to-talk and fullduplex dialed connections.

It will be recognized by those of ordinary skill in the art thatendpoints 22 and IS 20 may be any combination of hardware, software,and/or encoded logic that provides communication services to a user. Inthe illustrated embodiment, endpoints 22 comprise a PC (endpoint 22 a),a PDA (endpoint 22 b) and an IP phone 22 c). However, in otherembodiments, endpoints 22 may include a telephone, a personal computer(PC), a video monitor, a camera, an IP phone, a cell phone, a landmobile radio (LMR), a personal digital assistant (PDA), a command centeror any other communication hardware, software and/or encoded logic thatsupports the communication of audio, video or other data, using packetsof media (or frames) or otherwise, through communication system 10.Endpoints 22 as well as endpoints and components of communicationnetworks 24 may be capable of communicating using any particular type oftechnology, such as cellular, IP, PSTN, CDMA, GSM, TDMA and satellite.Endpoints 22 and IS 20 may also include unattended or automated systems,gateways, other intermediate components or other devices that canestablish media sessions.

Although the illustrated embodiment includes five communication networks24 a-24 e, the term “communication network” should be interpreted asgenerally defining any network capable of transmitting audio and/orvideo telecommunication signals, data, and/or messages, includingsignals, data or messages. Any one of networks 24 a-24 e may beimplemented as a local area network (LAN), wide area network (WAN),cellular network, global distributed network such as the Internet,Intranet, Extranet, PSTN, LMR network, CDMA network, GSM network, TDMAnetwork, satellite network or any other form of wireless or wirelinecommunication network.

Communications over communication networks 24 a-24 e may use anysuitable communication protocol. In a particular embodiment, somecommunication networks may employ voice communication protocols thatallow for the addressing or identification of endpoints, nodes, and/orother components coupled to the communication network. For example,using Internet protocol (IP), each of the components coupled togetherby, for example, communication network 24 b in communication system 10may be identified in information directed using IP addresses. In thismanner, network 24 b may support any form and/or combination ofpoint-to-point, multicast, unicast, or other techniques for exchangingmedia packets among components in communication system 10. Any networkcomponents capable of exchanging audio, video, or other data areincluded within the scope of the present invention.

Since IP networks share a common method of transmitting data,telecommunication signals may be transmitted between telephony deviceslocated on different, but interconnected, IP networks. In addition tobeing coupled to other IP networks, communication network 24 b may alsobe coupled to non-IP telecommunication networks, for example through theuse of interfaces or components, including gateways. In the illustratedembodiment, communication network 24 b may be coupled with PSTN 24 cthrough a gateway. In some embodiments the gateway may be a part of IS20 or network 24 e. PSTN 24 c includes switching stations, centraloffices, mobile telephone switching offices, pager switching offices,remote terminals, and other related telecommunications equipment thatare located throughout the world. IP networks transmit data (includingvoice and video data) by placing the data in packets and sending eachpacket individually to the selected destination, along one or morecommunication paths. Unlike a circuit-switched network (like PSTN 24 c),a dedicated circuit is not required for the duration of a call or faxtransmission over IP networks.

Technology that allows telecommunications to be transmitted over an IPnetwork may comprise Voice over IP (VoIP), or simply Voice over Packet(VoP). In the illustrated embodiment, one or more of endpoints 22, andendpoints and components of communication networks 24 may be IPtelephony devices capable of participating in IM, video, and othermultimedia communication sessions. IP telephony devices have the abilityof encapsulating a user's voice (or other input) into IP packets so thatthe voice can be transmitted over a communication network. IP telephonydevices may include telephones, fax machines, computers runningtelephony software, nodes, gateways, wired or wireless devices, handheld PDAs, or any other device capable of performing telephony functionsover an IP network.

In particular embodiments, communication system 10 may receive andtransmit data in a session initiation protocol (SIP) environment. SIP isan application-layer control protocol that includes primitives forestablishing, modifying and terminating communication sessions. SIPworks independently of underlying transport protocols and withoutdependency on the type of session that is being established. SIP alsotransparently supports name mapping and redirection services, whichsupport personal mobility.

Although FIG. 1 illustrates a particular number and configuration ofendpoints, IS and communication networks, communication system 10contemplates any number or arrangement of such components forcommunicating media.

FIG. 2 illustrates interoperability system (IS) 50, in accordance with aparticular embodiment. IS 50 may be similar to and provide the samefunctionality as IS 20 of FIG. 1. In the illustrated embodiment, IS 50includes interface 51, gateways 52, operations management application(OMA) 54, multipoint conference system (MCS) 56, policy engine 58,authentication and security system 60, call manager 62, processor 64 andmemory module 66. IS 50 is coupled to a PC endpoint 70 that may be usedto access, configure and control various functionality provided by IS50. PC endpoint 70 may run a client application for such access,configuration and control. The client application may enable a user ofendpoint 70 to receive and monitor communications from various endpointsand virtual talk groups. In particular embodiments, other types ofendpoints may be utilized to access, configure and control IS 50, suchas IP phones, PDAs and mobile devices. IS 50 may be coupled to suchendpoints (including PC endpoint 70) through one or more communicationnetworks.

Interface 51 is used in the communication of audio, video, signaling andother data between IS 50 and other network components. For example,interface 51 may receive communications from endpoints such as endpointsof communication networks 24, endpoints 22 and endpoint 70. Thecommunication may take place over IP networks thereby negating the needfor dedicated wiring between the endpoints and the IS.

Gateways 52 may include any suitable gateways to provide networkinteroperability and back-end legacy application integration, such asLMR gateways, PSTN gateways and application gateways. Gateways 52provide mapping between IP services and the interoperable networks, suchas LMR network 24 a of FIG. 1. In some cases gateways 52 may not belocated within an IS but may be distributed throughout a communicationsystem for enabling communications among various communication networks.

Operations management application (OMA) 54 includes functionality forconfiguration, management and control of IS 50, including conference andcollaboration management, and may be accessed by a user via, forexample, PC endpoint 70. In particular embodiments, OMA 54 may enable auser, such as dispatch personnel or administrators or a mobile user(e.g., a first responder mobile user) accessing IS 50 via a mobileendpoint, the ability to configure, manage and participate in one ormore virtual talk groups and ad hoc conferences simultaneously. Inparticular embodiments, OMA 54 may be accessed through a web interface,functioning for example as a soft phone for radios. A screen display maybe controlled using a mouse, keypad, touch screen, voice commands or anyother suitable interface. OMA 54 screens may include any number offunctional controls to provide interoperable communications. OMA 54 mayauthenticate a user and obtain user configuration information upon auser accessing the OMA. OMA 54 may monitor and provide communicationability for any number of channels at one time to provide the abilityfor an OMA user to communicate on and control multiple virtual talkgroups at once.

Multipoint conference system (MCS) 56 provides collaboration andconference services for multiple endpoints of one or more networks. Forexample, users of multiple endpoints (such as LMRs of different networks(e.g., networks of different agencies or groups) and different types ofendpoints of different networks) may be bridged together through MCS 56to provide virtual talk group communications. MCS 56 may include anysuitable number or type of conference bridges, ports, digital signalprocessors or other components to facilitate communications discussedherein.

Policy engine 58 includes policies for undertaking various operationsand functionality upon the occurrence of various events to providedynamic incident management. These policies may include bothpre-determined and ad hoc policies. For example, upon the occurrence ofa particular incident, the incident may include a unique identifier andmay have basic incident attributes such as time of creation, name ofuser creating and status. A pre-determined policy may then be executedby an incident manager or dispatch personnel as action for the specificincident. In particular embodiments, policy engine may receive inputsfrom alarms and sensors to setup device agnostic communicationsinteroperability and one-way video and data collaboration and to triggeradditional events such as pagers, e-mails, notifications, dial-outs,recording and information escalation.

Authentication and security system 60 manages access, configuration andcontrol privileges for users of IS 50 and those participating ininteroperable communications. For example, different users may havedifferent privileges assigned for interoperable communications. Someusers may only have transmit or listen privileges with respect to one ormore particular talk groups, while other users may have the ability tocommunicate in all talk groups or setup and configure various talkgroups. User privileges may change dynamically upon the occurrence ofparticular events.

Call manager 62 maintains information regarding various users, such asusers of IP networks for which interoperable communications are providedby IS 50. This facilitates in the extension of PTT to IP networks and inthe provision of voice and data interoperability across radio andnon-radio networks. In particular embodiments, call manager 62 maymaintain a listing, table, or other organization of information aboutusers. The information may include a name or other identifier andcontact information such as phone numbers and email addresses for theusers. In particular embodiments call manager 62 may represent anyappropriate combination of hardware, software and/or encoded logicdistributed throughout a communication network coupled with IS.

Processor 64 may be a microprocessor, controller, or any other suitablecomputing device, resource, or combination of hardware, software and/orencoded logic operable to provide, either alone or in conjunction withother IS components such as OMA 54, IS 50 functionality. Suchfunctionality may include providing various features discussed herein toa user, such as a user of an endpoint accessing IS 50 through OMA 54.Such features may include providing to the user endpoint locationinformation of communicating endpoints of a plurality of monitoredendpoints and/or virtual talk groups, enabling the user to listen toand/or participate in communications involving endpoints and/or virtualtalk groups of a particular geographic area, presenting communicationsof endpoints of scene-related virtual talk groups according topreconfigured or received instructions and controlling various gatewaysand other network components to facilitate interoperable communicationsamong various endpoints.

Memory module 66 may be any form of volatile or non-volatile memoryincluding, without limitation, magnetic media, optical media, randomaccess memory (RAM), read-only memory (ROM), removable media, or anyother suitable local or remote memory component. Memory module 66 maystore any suitable data or information, including software and encodedlogic, utilized by IS 50. In particular embodiments, memory module 66may include data for user management, talk-group management, resourcepool management, privileges, backup configuration and information and/ortimestamp and activity tracking.

IS 50 may also include any number of switches, routers, firewalls,mobile access routers, access points, wireless bridges and othercomponents in order to accommodate particular operational desires andneeds.

In particular embodiments such as in the LMR network interoperabilitycontext, IS 50 may, through one or more components discussed above orthrough other components, encode received audio with a standard audiocodec, such as G.711 or G.729. Those audio samples may be packaged instandards-based real-time transport protocol (RTP) packets suitable fortransport on an IP network. At this point, the communication element maybe abstracted from the distinctive characteristics of each radio system.These audio packets can be sent across the network to other radiosystems either individually (unicast) or as a group (multicast). Therecipient of the audio packets may be a device capable of receiving anddecoding the RTP stream, such as an IP telephone or PC with appropriatesoftware. The IP network and IP-enabled devices can be used to allowusers to monitor or transmit on a particular radio channel from a deskwithout issuing another radio.

As indicated above, IS 50 may facilitate communication among users ofendpoints of various networks through virtual channels or talk groups.For example, a channel may comprise a unidirectional or bidirectionalpath for transmitting and/or receiving electrical or electromagneticsignals. This may comprise, for example, a conventional radio physicalRF channel. A talk group in this context may be a subgroup of users(e.g., radio users) who share a common functional responsibility andtypically coordinate actions amongst themselves without radio interfacewith other subgroups. For example, a municipality's police departmentnetwork may include various talk groups of various users.

A virtual talk group (VTG) represents interoperability of a group ofchannels, for example, as an audio conference or meeting. A virtual talkgroup may include an associated virtual channel and an ID. Virtualchannels may comprise an address, such as an IP address, associated witha virtual talk group through which users may access the virtual talkgroup and/or through which communications from VTG member-endpoints arebridged. Various types of virtual talk groups may be utilized inparticular embodiments, such as a multicast address usable by allendpoints of the VTG, a VTG comprising multiple talk groups (e.g.,multiple radio sources from different frequencies whose communicationsare mixed), a unicast group and a combination unicast and multicastgroup.

As an example, a particular virtual talk group may comprise a conferenceor meeting of the following: (1) a channel or other multicast path usedby certain users of a police department's radio network, (2) a channelor other multicast path used by certain users of a fire department'sradio network, (3) a channel or other multicast path used by certainusers of a corporation's security radio network and (4) a plurality ofusers of IP-enabled endpoints such as IP phones, IP-enabled PDAs or PCs.An operator of IS 50 may configure the virtual talk group using anysuitable interface, such as by dragging and dropping the includedchannels and IP endpoints into a single area representing the virtualtalk group. MCS 56 may provide the functionality for the conference ofthe virtual talk group members. In particular embodiments, multiple talkgroups may be patched together on a dynamic, as needed basis. In somecases a virtual talk group may not necessarily include communicationsthrough an IS but may instead include member endpoints whosecommunications are mapped to IP addresses at gateways (such as LMRgateways) controlled by an IS.

Any number of virtual talk groups may be configured to provide anysuitable audio, data, video and control network interoperability.Virtual talk groups may be created using any suitable user/endpointgroups or channels based on location, organizational requirements, eventrequirements or any other suitable characteristic. An administrator oroperator may configure channel details such as name, description,participants, multicast IP addresses, codec and latch options through,for example, OMA 54.

FIG. 3 illustrates a system for providing a push-to-talk communicationsession, in accordance with a particular embodiment. The illustratedembodiment includes a full duplex endpoint 80 and a plurality ofhalf-duplex endpoints 90 coupled to an IS 100. It should be understoodthat FIG. 3 is only a logical illustration, and endpoints 80 and 90 maybe coupled to IS 100 through any number of communication networks, suchas an IP network. For example, IS 100 may act as a node coupled to an IPnetwork as illustrated with respect to IS 20 of FIG. 1. In some cases,communications between endpoints 80 and 90 may not travel through IS 100but may travel through gateways and other network components controlledby an IS. In particular embodiments, endpoints 80 and 90 a-90 c maycomprise endpoints of different communication networks or communicatingon different frequencies, such as endpoints of different policedepartments, fire departments or other security agencies or groups,including various users of a private organization or company. Endpoints80 and 90 a-90 c may typically communicate on their own communicationnetworks or on separate frequencies. In this case communications betweenendpoints 80 and 90 a-90 c are facilitated by IS 100 (e.g., bridgedthrough IS 100 in some cases) for interoperable communication with eachother in a virtual talk group using Internet Protocol as generallydescribed above with respect to FIGS. 1 and 2.

In the illustrated embodiment, endpoints 90 a and 90 b are part ofcommunication network 95 a, and endpoint 90 c is a part of communicationnetwork 95 b. Communication networks 95 a and 95 b may comprise, forexample, land mobile radio networks of different agencies or groups. Itshould be understood that endpoints 80 and 90 may communicate with IS100 through any of a variety of communication networks, such as one ormore WANs, LANs, cellular networks, PSTNs, LMR networks, CDMA networks,GSM networks, TDMA networks or satellite networks. IS 100 may be similarto, and may provide similar functionality as, IS 50 discussed above. IS100 may include the same or similar components as IS 50 and may alsoinclude a PTT floor control proxy system comprising any suitableprocessor or hardware, software or encoded logic to provide thefunctionality described herein.

Endpoint 80 may comprise a PSTN phone, cell phone or other suitable fullduplex endpoint and may include various functionality provided byendpoint 70 described above, such as the ability to access, configureand control various functionality provided by an IS and the ability torun a client application for such access, configuration and control. Inthe illustrated embodiment, endpoint 80 includes a transmitter/receiver82, a user interface 84, a processor 86 and a memory module 88.Transmitter/receiver 82 transmits and receives communications such asaudio, video, instant messaging and other data to and from other networkcomponents. User interface 84 provides a mechanism through which a userof endpoint 80 may operate the endpoint and communicate with othernetwork devices. Interface 84 may comprise, for example, a microphone, aspeaker, a keypad (e.g., for transmitting DTMF signals) or any othersuitable interface. Instructions may be submitted through speechrecognition, collection of keystrokes, soft key or otherwise.

Processor 86 may be a microprocessor, controller, or any other suitablecomputing device, resource, or combination of hardware, software and/orencoded logic operable to perform endpoint functionality. Processor 86,either alone or in conjunction with other endpoint components, providesendpoint functionality discussed herein. Memory module 88 may be anyform of volatile or non-volatile memory including, without limitation,magnetic media, optical media, random access memory (RAM), read-onlymemory (ROM), removable media, or any other suitable local or remotememory component.

Endpoint 80 comprises an endpoint capable of communicating in a fullduplex manner, such as a cellular phone. Thus, endpoint 80 may receiveand transmit communications at the same time using, for example,separate communication channels for incoming and outgoingcommunications. Endpoints 90 comprise any suitable half-duplex devices,such as push-to-talk land mobile radios. Thus, endpoints 90 may onlyeither transmit or receive communications at one time, as onecommunication channel is used for incoming and outgoing communications.As indicated above, particular embodiments provide a user of a fullduplex endpoint, such as endpoint 80, with the ability to communicatethrough PTT technology with one or more users of half-duplex endpoints,such as endpoints 90.

As an example, a user of a full duplex endpoint, such as endpoint 80,calls into IS 100 in order to participate in a virtual talk group ofusers of half-duplex, push-to-talk land mobile radios, such as endpoints90. A multipoint conference system of the IS may bridge togethertransmissions from an endpoint 80 or 90 for communication to the otherendpoints in the conference VTG, or IS 100 may otherwise facilitatecommunications among the endpoints. Since endpoint 80 is part of aconference of half-duplex endpoints, it must “control the floor” inorder to have its communications transmitted to and received by theother, half-duplex endpoints of the conference. Otherwise, its outgoingcommunications may not reach a half duplex endpoint 90 that is currentlysending a communication of its own and vice versa, since half duplexendpoints 90 communicate through a single channel. This floor controlmay be provided to endpoint 80 by IS 50 through a mute function. Forexample, when endpoint 80 is not muted, it controls the floor such thatits communications are transmitted to PTT endpoints 90 of the VTG. IS100 will prevent users of half duplex endpoints 90 from gaining controlof the floor at this time. However, when endpoint 80 is muted, then oneof PTT endpoints 90 may be able to control the floor to communicate tothe rest of the VTG, including to endpoint 80. The mute function may beactivated and deactivated by the user of endpoint 80 through anysuitable method, such as through a DTMF button of the endpoint whichtransmits a DTMF signal in the communication channel through whichendpoint 80 communicates with IS 50. In some embodiments, IS 50 mayforce full duplex endpoint 80 into mute whenever a half duplex endpointgains floor control.

When endpoint 80 calls into a VTG comprising one or more half-duplexdevices (e.g., endpoints 90), IS 100 may automatically mute the endpointand may notify its user that the endpoint is on mute. When IS 100 mutesendpoint 80, it may prevent its communications, such as its RTP packetstream in particular embodiments, from reaching the other endpoints ofthe VTG. IS 100 may provide the user of endpoint 80 with theinstructions of how to un-mute (e.g., pressing DTMF button 1 on hisendpoint) and how to mute (e.g., pressing DTMF button 0 on hisendpoint). In some cases, the same DTMF button may be used to mute andun-mute the endpoint.

When the user of endpoint 80 desires to “control the floor” in order tocommunicate with the half-duplex endpoints 90 of the VTG, the user mayun-mute the endpoint. Upon receiving the command to un-mute (e.g.,through a DTMF signal), IS 100 transmits a typical floor control signalto the other, half-duplex endpoints 90 such that they are not allowed tocommunicate in the VTG. This is similar to the manner in which a typicalPTT endpoint prevents other PTT endpoints communicating on a channelfrom communicating when the first PTT endpoint controls the floor. Aftermaking his desired communications, the user of endpoint 80 maysubsequently mute the endpoint in order to allow another endpoint tocontrol the floor and communicate on the VTG.

In particular embodiments, IS 100 may utilize the fact that endpoint 80is connected via a full duplex connection (e.g., another communicationchannel will be available to communication with endpoint 80) and mayprovide an audible signal to the user of endpoint 80 in order to givehim feedback that endpoint 80 is unmuted and thus has the floor. Thismay be similar to the typical PTT context whereby when a user of a PTT,half-duplex endpoint presses his “talk” button, he receives an audiblesignal when he has floor control allowing his communications to bereceived by the other PTT endpoints communicating on the same channel.The audio signal may comprise, for example, a “boink” sound signifyingthe granting of floor control by IS 100 to endpoint 80.

In particular embodiments, IS 100 may utilize other methods to signal toa user of endpoint 80 that endpoint 80 has control of the floor. In somecases, IS 100 may transmit a visual indicator (e.g., LED, instantmessage, e-mail, flash display, etc.) to endpoint 80 to signify floorcontrol. In some embodiments, IS 100 may provide floor controlconfirmation to endpoint 80 through vibrations. In other embodiments auser of endpoint 80 may have another, associated endpoint to which afloor control confirmation signal may be transmitted, whether audio,visual or otherwise. For example, endpoint 80 may comprise a full duplextelephone and the user of endpoint 80 may also have another endpoint,such as a PC, coupled to IS 100. IS 100 may transmit a floor controlconfirmation signal to the PC endpoint. This confirmation signal couldbe in any suitable form, such as an instant message, e-mail orotherwise.

If a user of endpoint 80 attempts to gain floor control (e.g., through aDTMF signal) when another endpoint such as one of PTT endpoints 90 hasthe floor, IS 100 may transmit a floor control denial signal to endpoint80 or another endpoint associated with the user of endpoint 80 to notifythe user that he cannot gain control of the floor at that time. Inparticular embodiments, such floor control denial signal may comprise anaudio “bonk” transmitted to endpoint 80. In other embodiments, suchfloor control denial signal may comprise another audio signal or avisual or vibratory signal transmitted to endpoint 80 or anotherendpoint associated with the user of endpoint 80 and coupled to IS 100,such as those described above with respect to the floor controlconfirmation signal.

In some embodiments, IS 100 may attempt to prevent a user of full-duplexendpoint 80 from controlling the floor for an extended amount of time(e.g., “locking the channel”) since, while the user controls the floor,he has the channel locked such that other PTT endpoints are preventedfrom communicating in the VTG. For example, if IS 100 determines that auser is talking longer than a particular amount of time (e.g., 2minutes), the system may utilize the full duplex capability of thecommunication channel to endpoint 80 to signal the user that he is aboutto be muted. In some cases, the user may not be talking and may haveforgotten that endpoint 80 was un-muted such that he had control of thefloor preventing endpoints 90 from communicating. Such a signal may takethe form of an audible tone or other signal, such as a whisperindication. In some cases, IS 100 may not signal the user of endpoint 80that he is about to be muted and may automatically mute the endpointwhen a maximum talk time is reached.

In some embodiments, IS 100 may have a policy that determines themaximum amount of time that a particular user may control the floor(e.g., a maximum talk time). This maximum talk time may vary by user.For example, higher priority users (e.g., higher ranked users or usersin higher positions within an organization) may be allotted a longermaximum talk time. In some cases, a maximum talk time for a usercommunicating on a full duplex endpoint in a VTG with users ofhalf-duplex devices may vary based on a type or priority of an eventassociated with the VTG. For example, higher priority events or eventsof a particular type (e.g., a terrorist event) may allow a shorter orlonger maximum talk time while lower priority events or events ofanother type (e.g., a car accident) may allow a different maximum talktime.

As described above, IS 100 enables a user of full duplex endpoint 80 toparticipate in PTT communications with, for example, PTT endpoints eventhough full duplex endpoint 80 may not understand or otherwise becapable of such participation.

FIG. 4A illustrates a system for providing a push-to-talk communicationsession using a control endpoint, in accordance with a particularembodiment. The illustrated embodiment includes a full duplex endpoint120, a control endpoint 122 and a plurality of half-duplex endpoints 130coupled to an IS 140. Similar to FIG. 3, FIG. 4A is only a logicalillustration, and endpoints 120, 122 and 130 may be coupled to IS 140through any of a number of communication networks, such as an IPnetwork. In some cases, communications between the illustrated endpointsmay not travel through IS 140 but may travel through gateways and othernetwork components controlled by an IS. While not specificallyillustrated, endpoints 120, 122 and 130 may be coupled to IS 140 throughone or more separate communication networks, such as land mobile radionetworks of separate groups or supporting communication on separatefrequencies, as discussed above with respect to endpoints 80 and 90 ofFIG. 3. Communication paths from endpoints 120 and 122 may traversedifferent networks. For example, a communication path from endpoint 120may traverse a PSTN network, and a communication path from endpoint 122may traverse a WAN.

In particular embodiments, endpoints 120, 122 and 130 may compriseendpoints of different communication networks, such as endpoints ofdifferent police departments, fire departments or other securityagencies or groups. Endpoints 120 and 130 (including endpoints 130 a-130c individually) may typically communicate on their own communicationnetworks on frequencies; but in this case their communications arebridged through IS 140 for interoperable communication with each otherin a virtual talk group using Internet Protocol. IS 140 may be similarto, and may provide similar functionality as, IS 50 discussed above.

Full duplex endpoint 120 and control endpoint 122 may each comprise anysuitable transmitter/receiver, user interface, processor and memorymodule. In some cases, full duplex endpoint 120 may comprise a rotaryphone incapable of transmitting DTMF or other control signals to IS 140.

In the illustrated embodiment, two different communication paths orchannels are used to provide full duplex endpoint 120 with the abilityto effectively communicate with half-duplex endpoints 130. Onecommunication path or channel may be used as a data channel tocommunicate the audio information, while another communication path orchannel may be used as a control channel to communicate PTT controls.Particular embodiments may terminate the data and control paths at thesame, full duplex endpoint such as endpoint 120. However, asillustrated, in some embodiments the data path and the control path mayterminate at different devices or endpoints. For example, a datacommunication path from endpoint 120 carries the audio that the user ofendpoint 120 requests to communicate to the users of endpoints 130 inthe VTG. A control communication path from endpoint 122 carries the PTTfloor control signal used by the user of control endpoint 122 to speakon the VTG. This control signal may be transmitted by the user throughcontrol endpoint 122, which is separate from endpoint 120 used by theuser to talk on the VTG. In some cases, the user may authenticatehimself at endpoint 122. This authentication will associate his use ofendpoint 122 with his audio transmissions from endpoint 120 to allow theuser to communicate in a PTT manner on endpoint 120 using endpoint 122as a floor control device.

The illustrated embodiment utilizes a signaling method for controllingthe PTT and floor control on behalf of full duplex endpoint 120. Controlendpoint 122 may be used to implement a self-moderated PTT control andmay include a separate PTT button 121 to control the floor through thecontrol path. Control endpoint 122 may comprise any of a number of typesof endpoints, such as a PC, a PDA or an IP phone and may interface withIS 140 to control the floor on PTT communications of full duplex 120using any suitable interface, such as a web interface. For example, aseparate button's floor control functionality may be implemented throughHTTP or XML in some cases. In some cases, floor control may be providedthrough a PTT soft button on, for example, a PDA or through a hardwaredevice such as a foot switch. In some cases, floor control may beprovided via instant messaging between a user and an IS. A user ofendpoint 120 may be in a PTT VTG (provided through or facilitated by IS140) with half-duplex endpoints 130. Endpoint 122 includes PTT button121 used by the user when the user wishes to gain floor control in orderto communicate to the group. When the user desires to talk, he may pressand hold PTT button 121. A floor control request signal is then sent toIS 140 which then sends a signal to half duplex endpoints 130 indicatingthat endpoint 120 has the floor to talk. IS 140 may also send a floorcontrol confirmation signal (e.g., audio, video, vibratory or otherwise)to endpoint 120, endpoint 122 or both to notify the user that he hascontrol of the floor. The user may then talk through endpoint 120, andthe user's audio may be communicated from endpoint 120 (e.g., through IS140 or otherwise) for transmittal to endpoints 130 of the VTG.Similarly, if another endpoint has control of the floor when the usersends the floor control signal via endpoint 122, then IS 140 maytransmit a floor control denial signal to endpoint 120, endpoint 122 orboth to notify the user that he cannot gain control of the floor at thattime. A user may also control other PTT functionality through controlendpoint 122, such as activation, deactivation, configuration functions,mute and un-mute.

It should be understood that particular embodiments may vary in themanner in which a user controls the floor through control endpoint 122.For example, in some cases the user may press button 121 to take controlof the floor and then press it again to relinquish floor control. Insome cases multiple buttons may be used. Some embodiments may not use abutton but may instead use another type of interface, such as a touchscreen display of control endpoint 122. Particular embodimentscontemplate great flexibility in the manner in which the PTT controlsignal is activated or used to control the floor to enable the user ofendpoint 120 to communicate in the VTG in a PTT manner with endpoints130. Using a separate endpoint as the source for the PTT control signalprovides particular advantages, including the ability to utilize a fullduplex endpoint that does not have DTMF capability (e.g., an olderrotary phone) in the PTT environment provided for full duplex endpointsthrough an IS.

In some embodiments that utilize separate channels for data and control,such separate channels may terminate at the same endpoint. For example,in some cases both the data path and control signal path may terminateat endpoint 120, and endpoint 120 may include PTT button 121 or othersuitable interface for floor control. This is similar to the embodimentsdiscussed with respect to FIG. 3 in which endpoint 80 was used both forthe audio communications and to gain control of the floor to speak.However, as discussed above, in embodiments described with respect toFIG. 4A the control signal is communicated in a different path (i.e., acontrol path) than the main talk or audio stream; and in FIG. 3 thecontrol signal was communicated in the main talk or data stream (e.g.,through DTMF signaling in that stream).

FIG. 4B illustrates another example of the use of a separate path orchannel for the control signaling used by a plurality of users of a fullduplex endpoint to communicate in a PTT virtual talk group. In theillustrated embodiment, full duplex endpoint 120 may be a phone in aconference room or another endpoint usable by multiple users toparticipate in a PTT VTG with half duplex endpoints 130. Controlendpoints 126 are coupled to IS 140 and are used by each userindividually to provide PTT floor control for the users. Controlendpoints 126 may comprise any suitable device for communicating a PTTcontrol signal to IS 140, such as a cell phone (endpoint 126 a), a PC(endpoint 126 b) or a PDA (endpoint 126 c). As described above withrespect to endpoints of other embodiments, full duplex endpoint 120,endpoints 126 and half duplex endpoints 130 may be coupled to IS 140through one or more communication networks, such as one or more WANs,LANs, cellular networks, PSTNs, LMR networks, CDMA networks, GSMnetworks, TDMA networks or satellite networks.

As an example in operation, endpoint 120 may be a full duplex conferencephone in a conference room and may be used to provide communications ina VTG through IS 140 with PTT endpoints 130. Control endpoints 126 a-126c may each comprise an endpoint of a respective person in the conferenceroom. Each such person uses endpoint 120 to talk on the VTG conference.Conference communications may be transmitted from endpoint 120 forcommunication to endpoints 130. However, each such person may use hisrespective endpoint 126 to control the floor of the conference when hedesires to talk. Such PTT floor control signals are transmitted to IS140 from the respective endpoint 126 along a control path (e.g., in asimilar manner as discussed above with respect to FIG. 4A). For example,when a user of cell phone endpoint 126 a desires to talk on theconference, he may press and hold a PTT button on his cell phone. Thissends a floor control signal to IS 140 which is transmitted to endpoints130 to indicate that a user of endpoint 120 has the floor. The cellphone user then speaks or otherwise communicates on the conferencethrough endpoint 120. The conference communications are communicated toIS 140 along a data path from endpoint 120. Similarly, when a user ofPDA 126 c desires to communicate on the VTG conference, he may gaincontrol of the floor by a control signal transmitted from endpoint 126 calong a control between endpoint 126 c and IS 140. The user may thentalk on the conference through endpoint 120. As is the case with otherembodiments, any number of interfaces or floor control activationmethods may be used, including web interfaces through endpoints 126. Insome embodiments, the control signals may be transmitted from endpoints126 to endpoint 120 for communication to IS 140. In this way, they maybe transmitted from endpoint 120 to IS 140 along a control path separatefrom the data path from endpoint 120.

In some cases, IS 140 may determine and identify a particular speakerbased on the endpoint from which the PTT control signal is transmitted.For example, when communication is made from endpoint 120 after a usergains floor control using his cell phone endpoint 126 a, IS 140 maydetermine that the person speaking is the user associated with endpoint126 a. This may be useful to other users of IS 140 in determining theidentity of a particular speaker out of a plurality of people in aconference room all using a full duplex conference room phone such asendpoint 120 for their VTG communications.

FIG. 5 illustrates a system 200 for providing a proxy media service, inaccordance with a particular embodiment. System 200 includes users 202and 204 who monitor push-to-talk communications of VTGs provided by IS210. IS 210 may be similar to IS 50 described above and may enableinteroperable VTG communications among endpoints of differentcommunication networks. In particular cases, users 202 and 204 maydesire to monitor at one time, through IS 210, communications from aplurality of different VTGs supported by the IS, each VTG comprising aconference media stream of PTT communications of respective endpoints ofthe VTG. In some cases, such users may monitor communications from eightseparate PTT VTG groups and may therefore receive eight separate mediastreams.

User 204 may access IS 210 through endpoint 205, which may comprise anysuitable endpoint for receiving multiple streams of PTT communicationsfor monitoring, such as a PC endpoint accessing the OMA of IS 210 andrunning a PC media client of the IS. Endpoint 205 is coupled to IS 210through a high bandwidth network 206, in this case a LAN. IS 210 maytransmit a communication stream for each of the plurality of monitoredVTGs, collectively communication streams 215, to endpoint 205 via highbandwidth network 206. As indicated above, in some cases communicationstreams 215 may comprise up to eight different media streams each from amonitored channel of PTT VTG communications. Endpoint 205 may then mixeach of the communications streams 215 for communication to user 204through a speaker or otherwise. In some cases, user 204 may use endpoint205 for changing the volume of one or more of the streams 215 withrespect to another of the streams or for providing other controlfunctionality.

In some situations, a user's access to IS 210 may be provided through alow bandwidth network that is only able to effectively communicate audiofrom one PTT VTG channel at one time. Thus, the low bandwidth network isnot able to effectively communicate the plurality of monitored PTT VTGcommunications in a separate stream for each VTG (e.g., in some casesthis may include eight streams) as can be done for endpoint 205accessing the IS through a LAN's high bandwidth connection. For example,a user may be accessing IS 210 via a low bandwidth WAN, such as througha DSL connection from home or away from a LAN at an office to which theIS is coupled. In particular embodiments a proxy media service may beused to mix the monitored streams into one stream for effectivecommunication to the user through the WAN. Likewise, the proxy mediaservice may also receive communications from the user over the WAN forcommunication over one or more of the monitored streams (or VTGs). Theproxy media service may also utilize a control path over the WAN toprovide control functionality to the user as desired. Examples of thiscontrol functionality are further discussed below. Therefore, particularembodiments provide a user connected over a low bandwidth WAN similarfunctionality and services for monitoring, communicating and withcontrolling a plurality of PTT VTGs as that provided to a user connectedthrough a high bandwidth LAN.

As an example in operation, user 202, utilizing endpoint 203, accessesIS 210 through low-bandwidth WAN 208. Endpoint 203 may comprise anysuitable endpoint accessing the OMA of IS 210 and running a PC mediaclient of the IS. In this example, since endpoint 203 is coupled to IS210 through a low bandwidth network, the individual communicationstreams from the monitored PTT VTGs are communicated to a proxy mediaservice (PMS) 220. IS 210 may transmit, direct and/or facilitate suchcommunication. For example, IS 210 may instruct PMS 220 to listen to aparticular multicast stream to enable PMS 220 to receive thecommunications on the stream. In some cases the communication streamsmay be sent from IS 210 to PMS 220. The media streams are collectivelyillustrated as communication streams 224 and may comprise a plurality ofstreams, each for a separate monitored PTT VTG channel. In some casescommunication streams 224 may include eight streams.

In the illustrated embodiment, PMS 220 includes a processor 221, adatabase 222 and a mixer 223. Processor 221 may be a microprocessor,controller, or any other suitable computing device, resource, orcombination of hardware, software and/or encoded logic operable toprovide, either alone or in conjunction with other PMS 220 componentssuch as mixer 223, PMS 220 functionality. Memory module 222 may be anyform of volatile or non-volatile memory including, without limitation,magnetic media, optical media, random access memory (RAM), read-onlymemory (ROM), removable media, or any other suitable local or remotememory component. Memory module 222 may store any suitable data orinformation, including software and encoded logic, utilized by PMS 220.

Mixer 223, in conjunction with processor 221, mixes the individualcommunication streams 224 received at PMS 220 into one stream so thatthe media may be effectively communicated to endpoint 203 via lowbandwidth network 208. Mixer 223 may comprise any hardware, software orencoded logic to provide its functionality.

Continuing the example described above, PMS 220 receives communicationstreams 224 and mixes them into one stream for communication to endpoint203 of user 202. The mixed stream of the plurality of communicationstreams 224 is represented as communication stream 225. Communicationstream 225 travels to endpoint 203 through low bandwidth network 208and, as discussed above, includes in one stream communications from eachof a plurality of PTT VTGs enabled by IS 210 that user 202 desires tomonitor. In some cases, this may include up to 8 separate PTT streamsmixed into communication stream 225. In some embodiments, endpoint 203may be connected to PMS 220 through a nailed connection.

In some embodiments, PMS 220 may also transmit to endpoint 203 anidentification of a VTG channel from which a particular communicationcomes. This may be displayed to user 202 by endpoint 203. This isparticular helpful to user 202 since endpoint 203 is receiving a singlestream 225 that comprises communications originating from a pluralitystreams. For example, user 202 may monitor VTGs 1-8 that are enabled byIS 210. A particular communication from, for example, VTG 5 may be mixedinto stream 225 and transmitted to endpoint 203. Since user 202 ismonitoring 8 different VTGs, he would not otherwise know that theparticular communication came from VTG 5 if not notified of this by PMS220. Thus, PMS 220 may transmit information signifying the channel ofVTG 5 as the source of a particular communication sent in communicationstream 225.

In addition, endpoint 203 may be able to receive communications on aplurality of channels. User 202 may, through a button of endpoint 203 orotherwise, notify PMS 220 of a particular channel in which to transmitmixed communication stream 225. For example, if the user selects channelB, then PMS 220 may receive communication streams 224 each communicatedon a different channel, mix them into one stream 225 and transmit thisstream to endpoint 203 on selected channel B.

In particular embodiments, user 202 may utilize a signaling or controlchannel between the endpoint and PMS 220 for controlling variousfeatures of PMS 220. For example, if the user wanted to change thevolume of a particular channel in the mixed stream 225, the user maytransmit such a request along the control path. In response, mixer 223and processor 221 may change the volume of the particular VTGscommunications relative to the other VTGs when mixing the communicationsfrom the various VTGs. The volume change will then be represented inmixed stream 225 communicated to endpoint 203.

A separate control or signaling path may also carry other userselections, such as a selection of a particular VTG channel to mix intostream 225. For example, IS 210 may be providing other VTGs that are notcurrently mixed into stream 225. User 202 may select one or more othersuch channels through the control or signaling path and PMS 220, inresponse, may receive communications from the selected VTG(s) and mixthem into stream 225 for communication to endpoint 203. Other controlfunctionality that may be provided through the control path may includeactivation and deactivation of particular VTG streams (for transmissionby PMS 220 and receipt at endpoint 203) and mute and un-mute ofparticular streams.

In addition, in particular embodiments user 202 may transmitcommunications to one or more of the VTG streams over the WAN. Forexample, the user may use endpoint 203 to speak, and such spokencommunication may be transmitted to PMS 220 for communication in one ormore of the PTT VTGs, through multicast, SIP nailed dialed connection,bridged communication or otherwise facilitated by IS 210. Thus, PMS 220enables the user to communicate a single stream over the WAN forcommunication to a plurality of VTG streams instead of the user havingto communicate (over the WAN) separate streams for each of the VTGs theuser desires to receive the communication.

The user may use the control path to identify a subset of the streamsmonitored by the PMS 220 to which the user's communications will betransmitted. For example, PMS 220 may be monitoring and mixing 8 VTGstreams for transmission to endpoint 203. However, the user at aparticular time may only desire to speak on 3 of such streams. Thus, theuser may use a PC softkey or other mechanism to identify the threestreams to which a particular communication from the user should betransmitted. This identification of the streams to which a particularcommunication from the user should be transmitted may be undertaken by aselection or other activation of the stream at the user endpoint. Then,when the user speaks, his communication is transmitted in a singlestream to PMS 220 which then forks the communication to the identifiedstreams. PMS 220 may transmit to the endpoint through an LED or othernotification an identification of the selected streams to which theuser's communication is transmitted. Thus, particular embodiments enablethe user to provide latch and unlatch speaking functionality over acontrol path to one or more of the streams monitored at PMS 220. This isadvantageous since many services providing internet connections over aWAN, such as many DSL services, provide a lower bandwidth for upstreamcommunications than that provided for downstream communications.

In particular embodiments, a system may, for example through PMS 220,have the ability to continuously analyze the available bandwidth overWAN 208 and the number of communication streams that the user wishes tomonitor and/or participate in. Based on this analysis, the system maydetermine whether to use the mixing capabilities of PMS 220 to mix suchstreams at the PMS or whether to send or receive the separate streamsfrom endpoint 203. For example, if user 202 desires to receive and/orcommunicate in 6 separate communication streams facilitated by IS 210and enough bandwidth exists over WAN 208 to convey each separate streamat an appropriate quality level, then the streams may be individuallytransmitted to endpoint 203 without mixing at PMS 220 and the user maycommunicate on the streams by endpoint 203 transmitting separatecommunications for each stream over WAN 208. If, however, enoughbandwidth does not exist over WAN 208 to convey each separate stream ata specified or appropriate quality level, then the streams may be mixedat PMS 220 for transmission as a mixed stream over WAN 208 to endpoint203 as discussed above. Moreover, as discussed above a singlecommunication stream from the user may be transmitted over WAN 208(e.g., “upstream”) and may be forked at PMS 220 for transmission on theuser's specified talk groups or channels. In this case, endpoint 203 mayinclude a processor (e.g., similar to the processor of PMS 220) or otherhardware, software or logic component for monitoring the bandwidth overWAN 208 and determining whether to send a user communication in a singlestream upstream to PMS 220 for forking at PMS 220 to each of auser-selected number of VTG streams or whether to send separate streamsover WAN 208 from the user endpoint for transmission to each of theuser-selected number of VTG streams. As indicated above, thedetermination may be based on whether the transmission of the separateindividual streams over WAN 208 can be accomplished at a specified orappropriate quality level. The acceptable service level needed to makethe determination over whether to use PMS 220 for mixing/forking may bedetermined, for example, by a system operator or administrator orotherwise. Call admission control functionality may be used in thisprocess for making such determination.

In some embodiments, user 202 may communicate on the monitored VTGsmixed into stream 225 in a similar manner as discussed above withrespect to embodiments providing PTT communication ability to fullduplex endpoints. In this case, PMS 220 may analyze and embed specificPTT tones to provide the user appropriate boinks and bonks such that theuser experience looks and feels like a native PTT user even though thefull duplex device has no knowledge of floor control.

As indicated above, particular embodiments provide a user connected overa low bandwidth WAN similar functionality and services for monitoring,communicating and with controlling a plurality of PTT VTGs as thatprovided to a user connected through a high bandwidth LAN. Thus, theappearance to the end user of LED and other indicators related to thePTT monitoring system's functionality will be the same regardless ofwhether mixing occurs using a proxy media service or whether the user'sendpoint actually can receive/transmit and mix for presentation to theuser separate streams for each monitored stream. As discussed above,these indicators may be used to indicate, for example, which stream(s)are currently being monitored, on which stream(s) a particular usercommunication is currently being transmitted (e.g., latch/unlatchnotification), floor control, mute/unmute and other functionality. Inaddition, the PTT functionality for the end user may be the sameregardless of whether the user is accessing the system over a WAN or aLAN. Thus, the PTT functionality provided to the end user may beindependent of the user's location.

FIG. 6 is a flowchart illustrating a method for providing a push-to-talkcommunication session, in accordance with a particular embodiment. Themethod begins at step 300 where a push-to-talk communication sessionamong a full duplex endpoint and a plurality of half duplex endpoints isfacilitated. The full duplex endpoint may support simultaneous two-waycommunication to and from the endpoint. The half duplex endpoints mayonly be able to either transmit or receive communications at one time.Communications are received from and transmitted to the full duplexendpoint along a two-way communications path. The half duplex endpointsmay include endpoints of different communication networks, such asendpoints that typically communicate on different frequencies. Thecommunication session may be facilitated using IP by an interoperabilitysystem bridging communications or controlling gateways or other networkcomponents.

At step 302, communications received from the full duplex endpoint areblocked while one of the plurality of half duplex endpoints has floorcontrol in the communication session. At step 304, a floor controlsignal is received from the full duplex endpoint in the two-waycommunications path. The floor control signal comprises a request totransmit communications in the communication session and may comprise aDTMF signal.

At step 306, in response to receiving the floor control signal, floorcontrol is provided to the full duplex endpoint to allow a user of thefull duplex endpoint to communicate in the communication session. Insome cases, a confirmation signal such as a bonk may be transmitted tothe full duplex endpoint to signify that the full duplex endpoint hascontrol of the floor. The floor control confirmation signal may includeany suitable audio, visual or vibratory signal. In some embodiments, thefloor control confirmation signal may be transmitted to another endpointassociated with the user of the full duplex endpoint, such as through aninstant message, an e-mail, or another visual signal to a PC of theuser. At step 308, communications received from the full duplex endpointare transmitted to the plurality of half duplex endpoints.

In some cases, the full duplex endpoint is only allowed to maintaincontrol of the floor for a certain amount of time. At step 310, floorcontrol of the full duplex endpoint is terminated after a maximum floorcontrol amount of time to allow the half duplex endpoints to communicatein the communication session. The maximum floor control amount of timemay be determined based on a particular user of the full duplexendpoint, an event associated with the communication session or otherfactors.

FIG. 7 illustrates a method for providing a push-to-talk communicationsession using a control endpoint, in accordance with a particularembodiment. The method begins at step 400 where a push-to-talkcommunication session among a full duplex endpoint and a plurality ofhalf duplex endpoints is facilitated. The full duplex endpoint maysupport simultaneous two-way communication to and from the endpoint. Thehalf duplex endpoints may only be able to either transmit or receivecommunications at one time. Communications are received from andtransmitted to the full duplex endpoint along a two-way communicationspath. The half duplex endpoints may include endpoints of differentcommunication networks, such as endpoints that typically communicate ondifferent frequencies. The communication session may be facilitatedusing IP by an interoperability system bridging communications orcontrolling gateways or other network components.

At step 402, communications received from the full duplex endpoint areblocked while one of the plurality of half duplex endpoints has floorcontrol in the communication session. At step 404, a floor controlsignal is received from a control endpoint separate from the full duplexendpoint. The floor control signal comprises a request to transmitcommunications in the communication session. In some cases the controlendpoint may be a user's cell phone, PC, IP phone or PDA. In some casesthe control signal may be received via a web, instant messaging, HTTP orXML interface.

At step 406, in response to receiving the floor control signal, floorcontrol is provided to the full duplex endpoint to allow a user of thefull duplex endpoint to communicate in the communication session. Insome cases, a confirmation signal such as a bonk or boink may betransmitted to the user of the full duplex endpoint, for example throughthe full duplex endpoint, the control endpoint or otherwise, to signifythat the full duplex endpoint has control of the floor. At step 408,communications received from the full duplex endpoint are transmitted tothe plurality of half duplex endpoints. It should be understood thatalthough “bonk” and “boink” are used to describe audio sounds herein, itshould be understood that any suitable audio sound may be used to conveythe applicable messages or indications as those conveyed by thedescribed bonks and boinks.

In some embodiments the full duplex endpoint may be used by a pluralityof users to communicate in the communication session, and each of theplurality of users may transmit a control signal to gain floor controlin the session using their own respective devices, such as cell phones,PDAs, PCs and IP phones. As an example, the plurality of users may besitting in a conference room in which the full duplex endpoint sits.When a particular user in the room desires to speak in the session, theuser may transmit a floor control request signal from that user'spersonal endpoint. The floor signal may be received at aninteroperability system facilitating the communication session whichthen provides the user with floor control to speak in the session. Insome cases in which multiple endpoints are used to gain control of thefloor to speak through a full duplex endpoint, the system may identify aparticular speaker based on the endpoint used to transmit thepush-to-talk floor control signal.

FIG. 8 illustrates a method for providing a push-to-talk proxy mediaservice, in accordance with a particular embodiment. The method beginsat step 500 where a plurality of monitored communication streams, suchas push-to-talk communication streams, are received over a highbandwidth connection. The communication streams may be monitored at aninteroperability system that facilitates interoperable communications invirtual talk groups among endpoints of various communication networks.The monitored streams may be received at a proxy media system coupled toa high bandwidth network to which the interoperability system iscoupled.

At step 502, the plurality of monitored push-to-talk communicationstreams are mixed into a mixed communication stream. Such mixing maytake place at the proxy media system. At step 504, the mixedcommunication stream is transmitted over a low bandwidth connection to auser endpoint. For example, a user may be using a low bandwidth networksuch as a WAN to access a high bandwidth network, such as a LAN, from ahome computer or other endpoint away from the LAN. The proxy mediasystem may be coupled to the LAN and may transmit the mixedcommunication stream to the user over the low bandwidth WAN.

As indicated above, in some cases the monitored communication streamsmay each comprise a stream of a virtual talk group configured by aninteroperability system. In some cases, at step 506, an identificationof a particular speaker's or communication's virtual talk group may betransmitted to the user (e.g., in the mixed stream). For example, if themixed stream at one point includes communications from VTG 4, then anidentification of VTG 4 may be transmitted when such communication fromVTG 4 is transmitted to the user.

In some embodiments, the user endpoint may use a separate control pathto transmit instructions to the proxy media system, such as instructionsto adjust the volume of a particular VTG's stream relative to otherVTGs' streams when mixing the monitored communication streams. In somecases the user endpoint may be operable to receive the mixed stream onany of a number of channels, and the user endpoint may use the separatecontrol path to transmit a channel selection for receipt of the mixedstream. In addition, in some embodiments the user endpoint may, throughthe control path, instruct the proxy media system to mix certain streams(e.g., streams from certain, selected VTGs) out of all the monitoredcommunication streams received from the interoperability system.

Some of the steps illustrated in FIGS. 6-8 may be combined, modified ordeleted where appropriate, and additional steps may also be added to theflowcharts. Additionally, steps may be performed in any suitable orderwithout departing from the scope of the invention.

While various implementations and features are discussed with respect tomultiple embodiments, it should be understood that such implementationsand features may be combined in various embodiments. For example,features and functionality discussed with respect to a particular figuremay be used in connection with features and functionality discussed withrespect to another such figure according to operational needs ordesires.

Although the present invention has been described in detail withreference to particular embodiments, it should be understood thatvarious other changes, substitutions, and alterations may be made heretowithout departing from the spirit and scope of the present invention.For example, although the present invention has been described withreference to a number of elements included within communication system10 and illustrated endpoints and interoperability systems, theseelements may be combined, rearranged or positioned in order toaccommodate particular routing architectures or needs. In addition, anyof these elements may be provided as separate external components tocommunication system 10 and illustrated endpoints and interoperabilitysystems, or each other where appropriate. The present inventioncontemplates great flexibility in the arrangement of these elements aswell as their internal components.

Numerous other changes, substitutions, variations, alterations andmodifications may be ascertained by those skilled in the art and it isintended that the present invention encompass all such changes,substitutions, variations, alterations and modifications as fallingwithin the spirit and scope of the appended claims.

1. A method for providing a push-to-talk proxy media service, comprising: receiving a plurality of monitored push-to-talk communication streams over a high bandwidth connection, each monitored push-to-talk communication stream comprising audio communications from a plurality of users; mixing the plurality of monitored push-to-talk communication streams into a mixed communication stream such that the audio communications communicated in each of the monitored push-to-talk communication streams can be heard on the mixed stream; and transmitting the mixed communication stream to a user endpoint over a low bandwidth connection.
 2. The method of claim 1, wherein each of the push-to-talk communication streams comprises communications from a respective virtual talk group comprising a plurality of endpoints of different communication networks.
 3. The method of claim 2: wherein the mixed communication stream comprises a first communication of a first virtual talk group; and further comprising transmitting an identification of the first virtual talk group when transmitting the mixed communication stream comprising the first communication.
 4. The method of claim 2, wherein the plurality of monitored push-to-talk communication streams are received over the high bandwidth connection from an interoperability system operable to configure each virtual talk group to facilitate communications among its member endpoints.
 5. The method of claim 2, wherein at least one of the virtual talk groups comprises a plurality of endpoints of different communication networks whose communications are mapped to a multicast IP address or SIP dialed nailed connection.
 6. The method of claim 2, wherein at least one of the virtual talk groups comprises a plurality of endpoints of different communication networks whose communications are bridged.
 7. The method of claim 1, wherein receiving a plurality of monitored push-to-talk communication streams comprises receiving eight monitored push-to-talk communication streams.
 8. The method of claim 1, further comprising: receiving from the user endpoint volume instructions associated with at least one of the push-to-talk communication streams; and adjusting the volume of the at least one of the push-to-talk communication streams according to the instructions when mixing the plurality of monitored push-to-talk communication streams into a mixed communication stream.
 9. The method of claim 1: further comprising receiving from the user endpoint a selection of a group of the push-to-talk communication streams for mixing; and wherein mixing the plurality of monitored push-to-talk communication streams into a mixed communication stream comprises mixing the selected group of the push-to-talk communication streams into a mixed communication stream.
 10. The method of claim 2, further comprising receiving from the user over the low bandwidth connection: a user communication; and a selection of a plurality of virtual talk groups of the respective virtual talk groups; and transmitting the received user communication to the selected plurality of virtual talk groups over the high bandwidth connection.
 11. The method of claim 10, further comprising transmitting to the user endpoint an identification of the selected plurality of virtual talk groups when transmitting the received user communication to the selected plurality of virtual talk groups.
 12. The method of claim 1, further comprising presenting functionality indicators for a user at the user endpoint in the same manner as if the plurality of monitored push-to-talk communication streams had been individually transmitted over a high bandwidth connection to the user endpoint and mixed at the user endpoint for the user.
 13. A system for providing a push-to-talk proxy media service, comprising: an interface operable to receive a plurality of monitored push-to-talk communication streams over a high bandwidth connection, each monitored push-to-talk communication stream comprising audio communications from a plurality of users; a mixer coupled to the interface and operable to mix the plurality of monitored push-to-talk communication streams into a mixed communication stream such that the audio communications communicated in each of the monitored push-to-talk communication streams can be heard on the mixed stream; and a processor operable to transmit the mixed communication stream to a user endpoint over a low bandwidth connection.
 14. The system of claim 13, wherein each of the push-to-talk communication streams comprises communications from a respective virtual talk group comprising a plurality of endpoints of different communication networks.
 15. The system of claim 14: wherein the mixed communication stream comprises a first communication of a first virtual talk group; and wherein the processor is further operable to transmit an identification of the first virtual talk group when transmitting the mixed communication stream comprising the first communication.
 16. The system of claim 14, wherein the plurality of monitored push-to-talk communication streams are received over the high bandwidth connection from an interoperability system operable to configure each virtual talk group to facilitate communications among its member endpoints.
 17. The system of claim 14, wherein at least one of the virtual talk groups comprises a plurality of endpoints of different communication networks whose communications are mapped to a multicast IP address or SIP dialed nailed connection.
 18. The system of claim 14, wherein at least one of the virtual talk groups comprises a plurality of endpoints of different communication networks whose communications are bridged.
 19. The system of claim 13, wherein an interface operable to receive a plurality of monitored push-to-talk communication streams comprises an interface operable to receive eight monitored push-to-talk communication streams.
 20. The system of claim 13, wherein: the interface is further operable to receive from the user endpoint volume instructions associated with at least one of the push-to-talk communication streams; and the mixer is further operable to adjust the volume of the at least one of the push-to-talk communication streams according to the instructions when mixing the plurality of monitored push-to-talk communication streams into a mixed communication stream.
 21. The system of claim 13, wherein: the interface is further operable to receive from the user endpoint a selection of a group of the push-to-talk communication streams for mixing; and a processor operable to mix the plurality of monitored push-to-talk communication streams into a mixed communication stream comprises a processor operable to mix the selected group of the push-to-talk communication streams into a mixed communication stream.
 22. The system of claim 14, wherein: the interface is operable to receive from the user over the low bandwidth connection: a user communication; and a selection of a plurality of virtual talk groups of the respective virtual talk groups; and the processor is operable to transmit the received user communication to the selected plurality of virtual talk groups over the high bandwidth connection.
 23. The system of claim 22, wherein the processor is further operable to transmit to the user endpoint an identification of the selected plurality of virtual talk groups when transmitting the received user communication to the selected plurality of virtual talk groups.
 24. The system of claim 13, wherein the processor is further operable to present functionality indicators for a user at the user endpoint in the same manner as if the plurality of monitored push-to-talk communication streams had been individually transmitted over a high bandwidth connection to the user endpoint and mixed at the user endpoint for the user.
 25. A system for providing a push-to-talk proxy media service, comprising: means for receiving a plurality of monitored push-to-talk communication streams over a high bandwidth connection, each monitored push-to-talk communication stream comprising audio communications from a plurality of users; means for mixing the plurality of monitored push-to-talk communication streams into a mixed communication stream such that the audio communications communicated in each of the monitored push-to-talk communication streams can be heard on the mixed stream; and means for transmitting the mixed communication stream to a user endpoint over a low bandwidth connection.
 26. Logic embodied in a non-transitory computer readable medium, the non-transitory computer readable medium comprising code operable to: receive a plurality of monitored push-to-talk communication streams over a high bandwidth connection, each monitored push-to-talk communication stream comprising audio communications from a plurality of users; mix the plurality of monitored push-to-talk communication streams into a mixed communication stream such that the audio communications communicated in each of the monitored push-to-talk communication streams can be heard on the mixed stream; and transmit the mixed communication stream to a user endpoint over a low bandwidth connection.
 27. The non-transitory computer readable medium of claim 26, wherein each of the push-to-talk communication streams comprises communications from a respective virtual talk group comprising a plurality of endpoints of different communication networks.
 28. The non-transitory computer readable medium of claim 27: wherein the mixed communication stream comprises a first communication of a first virtual talk group; and wherein the code is further operable to transmit an identification of the first virtual talk group when transmitting the mixed communication stream comprising the first communication.
 29. The non-transitory computer readable medium of claim 27, wherein the plurality of monitored push-to-talk communication streams are received over the high bandwidth connection from an interoperability system operable to configure each virtual talk group to facilitate communications among its member endpoints.
 30. The non-transitory computer readable medium of claim 27, wherein at least one of the virtual talk groups comprises a plurality of endpoints of different communication networks whose communications are mapped to a multicast IP address or SIP dialed nailed connection.
 31. The non-transitory computer readable medium of claim 27, wherein at least one of the virtual talk groups comprises a plurality of endpoints of different communication networks whose communications are bridged.
 32. The non-transitory computer readable medium of claim 26, wherein code operable to receive a plurality of monitored push-to-talk communication streams comprises code operable to receive eight monitored push-to-talk communication streams.
 33. The non-transitory computer readable medium of claim 26, wherein the code is further operable to: receive from the user endpoint volume instructions associated with at least one of the push-to-talk communication streams; and adjust the volume of the at least one of the push-to-talk communication streams according to the instructions when mixing the plurality of monitored push-to-talk communication streams into a mixed communication stream.
 34. The non-transitory computer readable medium of claim 26: wherein the code is further operable to receive from the user endpoint a selection of a group of the push-to-talk communication streams for mixing; and wherein code operable to mix the plurality of monitored push-to-talk communication streams into a mixed communication stream comprises code operable to mix the selected group of the push-to-talk communication streams into a mixed communication stream.
 35. The non-transitory computer readable medium of claim 26, wherein the code is further operable to: receive from the user over the low bandwidth connection: a user communication; and a selection of a plurality of virtual talk groups of the respective virtual talk groups; and transmit the received user communication to the selected plurality of virtual talk groups over the high bandwidth connection.
 36. The non-transitory computer readable medium of claim 35, wherein the code is further operable to transmit to the user endpoint an identification of the selected plurality of virtual talk groups when transmitting the received user communication to the selected plurality of virtual talk groups.
 37. The non-transitory computer readable medium of claim 36, wherein the code is further operable to present functionality indicators for a user at the user endpoint in the same manner as if the plurality of monitored push-to-talk communication streams had been individually transmitted over a high bandwidth connection to the user endpoint and mixed at the user endpoint for the user.
 38. A method for providing a push-to-talk proxy media service, comprising: receiving from a user endpoint over a low bandwidth connection: a user communication; and a selection of a plurality of virtual talk groups, each virtual talk group comprising a push-to-talk communication stream comprising communications from a plurality of endpoints of different communication networks, each push-to-talk communication stream comprising audio communications from a plurality of users; and transmitting the received user communication to each of the selected plurality of virtual talk groups over a high bandwidth connection.
 39. The method of claim 38, further comprising transmitting to the user endpoint an identification of the selected plurality of virtual talk groups when transmitting the received user communication to the selected plurality of virtual talk groups. 